U.S. patent application number 10/331839 was filed with the patent office on 2003-07-03 for apparatus and method for transmitting/receiving a high speed-shared control channel in a high speed downlink packet access communication system.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Kim, Hun-Kee, Kim, No-Sun, Lee, Jun-Sung, Moon, Yong-Suk, Yoon, Jae-Seung.
Application Number | 20030123470 10/331839 |
Document ID | / |
Family ID | 19717830 |
Filed Date | 2003-07-03 |
United States Patent
Application |
20030123470 |
Kind Code |
A1 |
Kim, No-Sun ; et
al. |
July 3, 2003 |
Apparatus and method for transmitting/receiving a high speed-shared
control channel in a high speed downlink packet access
communication system
Abstract
An apparatus and method for transmitting/receiving an HS-SCCH in
an HSDPA communication system including an HS-DSCH shared among a
plurality of UEs and spread with a plurality of channelization
codes, and the HS-SCCH for transmitting control information related
with the HS-DSCH to enable the UEs to receive the shared channel.
In the HS-SCCH transmitting apparatus, the control information is
prioritized according to its processing urgency degree.
High-priority control information and low-priority control
information are generated and encoded in different encoding
methods. Then the high-priority control information and the
low-priority control information are multiplexed to a control
channel signal such that the high-priority control information
precedes the low-priority control information.
Inventors: |
Kim, No-Sun; (Suwon-shi,
KR) ; Moon, Yong-Suk; (Songnam-shi, KR) ; Kim,
Hun-Kee; (Seoul, KR) ; Yoon, Jae-Seung;
(Songnam-shi, KR) ; Lee, Jun-Sung; (Suwon-shi,
KR) |
Correspondence
Address: |
Paul J. Farrell, Esq.
DILWORTH & BARRESE, LLP
333 Earle Ovington Blvd.
Uniondale
NY
11553
US
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Kyungki-Do
KR
|
Family ID: |
19717830 |
Appl. No.: |
10/331839 |
Filed: |
December 30, 2002 |
Current U.S.
Class: |
370/437 ;
370/462 |
Current CPC
Class: |
H04J 13/20 20130101;
H04W 72/1289 20130101; H04L 1/1887 20130101; H04L 1/0003 20130101;
H04L 2001/0098 20130101; H04B 7/2637 20130101; H04J 13/0044
20130101; H04W 72/1242 20130101; H04L 1/1819 20130101; H04L 1/1803
20130101 |
Class at
Publication: |
370/437 ;
370/462 |
International
Class: |
H04J 003/16 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 2001 |
KR |
2001/87296 |
Claims
What is claimed is:
1. A control channel transmitting apparatus in a communication
system including a shared channel and a control channel, the shared
channel being shared among a plurality of UEs (User Equipments) and
spread with a plurality of channelization codes, and the control
channel transmitting control information related to the shared
channel to enable the UEs to receive the shared channel, the
apparatus comprising: a controller for prioritizing the control
information according to a processing urgency degree of the control
information; a first control information generator for generating
high-priority control information; a second control information
generator for generating low-priority control information; a first
encoder for encoding the high-priority control information in a
predetermined first encoding method; a second encoder for encoding
the low-priority control information in a predetermined second
encoding method different from the first encoding method; and a
multiplexer (MUX) for multiplexing the high-priority control
information and the low-priority control information to a control
channel signal such that the high-priority control information
precedes the low-priority control information.
2. The control channel transmitting apparatus of claim 1, wherein
the high-priority control information includes information about a
channelization code to spread the shared channel with, and a
modulation scheme applied to the shared channel.
3. The control channel transmitting apparatus of claim 1, wherein
the low-priority control information includes information about a
new data indicator indicating whether the user data is initially
transmitted or retransmitted on the shared channel, a transport
block set size of a transport channel mapped to the shared channel,
redundancy version information indicating a redundancy bit
combination used for retransmitted user data if the user data is
retransmitted, and an HARQ (Hybrid Automatic Repeat reQuest)
process ID (Identifier) indicating a number of a logical channel
that transmits the user data.
4. The control channel transmitting apparatus of claim 3, wherein
when the user data is initially transmitted, the controller
controls the redundancy version information not to be generated,
and when the user data is retransmitted, the controller controls
the transport block set size information not to be generated.
5. The control channel transmitting apparatus of claim 1, wherein
the high-priority control information includes information about a
channelization code to spread the shared channel with, and a new
data indicator indicating whether user data is initially
transmitted or retransmitted on the shared channel.
6. The control channel transmitting apparatus of claim 1, wherein
the low-priority control information includes information about a
modulation scheme applied to the shared channel, a transport block
set size of a transport channel mapped to the shared channel,
redundancy version information indicating a redundancy bit
combination used for retransmitted user data if the user data is
retransmitted, and an HARQ Process ID indicating a number of a
logical channel that transmits the user data.
7. The control channel transmitting apparatus of claim 6, wherein
when the user data is initially transmitted, the controller
controls the redundancy version information not to be generated,
and when the user data is retransmitted, the controller controls
the transport block set size information not to be generated.
8. The control channel transmitting apparatus of claim 1, wherein
the high-priority control information includes information about a
channelization code to spread the shared channel with, a modulation
scheme applied to the shared channel, and a new data indicator
indicating whether user data is initially transmitted or
retransmitted on the shared channel.
9. The control channel transmitting apparatus of claim 1, wherein
the low-priority control information includes information about the
transport block set size of a transport channel mapped to the
shared channel, redundancy version information indicating a
redundancy bit combination used for retransmitted user data if the
user data is retransmitted, and an HARQ Process ID indicating a
number of a logical channel that transmits the user data.
10. The control channel transmitting apparatus of claim 9, wherein
when the user data is initially transmitted, the controller
controls the redundancy version information not to be generated,
and when the user data is retransmitted, the controller controls
the transport block set size information not to be generated.
11. A control channel receiving apparatus in a communication system
including a shared channel and a control channel, the shared
channel being shared among a plurality of UEs (User Equipments) and
spread with a plurality of channelization codes, and the control
channel transmitting control information related to the shared
channel to enable the UEs to receive the shared channel, the
apparatus comprising: a demultiplexer (DEMUX) for receiving a
control channel signal and demultiplexing the control channel
signal into high-priority control information and low-priority
control information according to processing urgency degrees of the
control information under a predetermined control; a first decoder
for decoding the high-priority control information in a
predetermined first decoding method; a second decoder for decoding
the low-priority control information in a predetermined second
decoding method different from the first decoding method; and a
controller for controlling the high-priority control information to
be demodulated before the low-priority control information.
12. The control channel receiving apparatus of claim 11, wherein
the high-priority control information includes information about a
channelization code to spread the shared channel with, and a
modulation scheme applied to the shared channel.
13. The control channel receiving apparatus of claim 11, wherein
the low-priority control information includes information about a
new data indicator indicating whether user data is initially
transmitted or retransmitted on the shared channel, a transport
block set size of a transport channel mapped to the shared channel,
redundancy version information indicating a redundancy bit
combination used for retransmitted user data if the user data is
retransmitted, and an HARQ (Hybrid Automatic Repeat reQuest)
process ID (Identifier) indicating a number of a logical channel
that transmits the user data.
14. The control channel receiving apparatus of claim 13, wherein
when the user data is initial transmission data, the controller
determines that the low-priority control information includes the
transport block set size information.
15. The control channel receiving apparatus of claim 11, wherein
the high-priority control information includes information about a
channelization code to spread the shared channel with, and a new
data indicator indicating whether user data is initially
transmitted or retransmitted on the shared channel.
16. The control channel receiving apparatus of claim 11, wherein
the low-priority control information includes information about a
modulation scheme applied to the shared channel, a transport block
set size of a transport channel mapped to the shared channel,
redundancy version information indicating a redundancy bit
combination used for retransmitted user data if the user data is
retransmitted, and an HARQ Process ID indicating a number of a
logical channel that transmits the user data.
17. The control channel receiving apparatus of claim 16, wherein
when the user data is initial transmission data, the controller
determines that the low-priority control information includes the
transport block set size information.
18. The control channel receiving apparatus of claim 11, wherein
the high-priority control information includes information about a
channelization code to spread the shared channel with, a modulation
scheme applied to the shared channel, and a new data indicator
indicating whether user data is initially transmitted or
retransmitted on the shared channel.
19. The control channel receiving apparatus of claim 11, wherein
the low-priority control information includes information about a
transport block set size of a transport channel mapped to the
shared channel, redundancy version information indicating a
redundancy bit combination used for retransmitted user data if the
user data is retransmitted, and an HARQ Process ID indicating a
number of a logical channel that transmits the user data.
20. The control channel receiving apparatus of claim 19, wherein
when the user data is initial transmission data, the controller
determines that the low-priority control information includes the
transport block set size information.
21. A control channel transmitting method in a communication system
including a shared channel and a control channel, the shared
channel being shared among a plurality of UEs (User Equipments) and
spread with a plurality of channelization codes, and the control
channel transmitting control information related to the shared
channel to enable the UEs to receive the shared channel, the method
comprising the steps of: prioritizing the control information
according to a processing urgency degree of the control
information; generating high-priority control information and
encoding the high-priority control information in a predetermined
first encoding method; generating low-priority control information
and encoding the low-priority control information in a
predetermined second encoding method different from the first
encoding method; and multiplexing the high-priority control
information and the low-priority control information to a control
channel signal such that the high-priority control information
precedes the low-priority control information.
22. The control channel transmitting method of claim 21, wherein
the high-priority control information includes information about a
channelization code to spread the shared channel with, and a
modulation scheme applied to the shared channel.
23. The control channel transmitting method of claim 21, wherein
the low-priority control information includes information about a
new data indicator indicating whether user data is initially
transmitted or retransmitted on the shared channel, a transport
block set size of a transport channel mapped to the shared channel,
redundancy version information indicating a redundancy bit
combination used for retransmitted user data if the user data is
retransmitted, and an HARQ (Hybrid Automatic Repeat reQuest)
process ID (Identifier) indicating a number of a logical channel
that transmits the user data.
24. The control channel transmitting method of claim 23, further
comprising the step of controlling the redundancy version
information not to be generated when the user data is initially
transmitted, and controlling the transport block set size
information not to be generated when the user data is
retransmitted.
25. The control channel transmitting method of claim 21, wherein
the high-priority control information includes information about a
channelization code to spread the shared channel with, and a new
data indicator indicating whether user data is initially
transmitted or retransmitted on the shared channel.
26. The control channel transmitting method of claim 21, wherein
the low-priority control information includes information about a
modulation scheme applied to the shared channel, a transport block
set size of a transport channel mapped to the shared channel,
redundancy version information indicating a redundancy bit
combination used for retransmitted user data if the user data is
retransmitted, and an HARQ Process ID indicating a number of a
logical channel that transmits the user data.
27. The control channel transmitting method of claim 26, further
comprising the step of controlling the redundancy version
information not to be generated when the user data is initially
transmitted, and controlling the transport block set size
information not to be generated when the user data is
retransmitted.
28. The control channel transmitting method of claim 21, wherein
the high-priority control information includes information about a
channelization code to spread the shared channel with, a modulation
scheme applied to the shared channel, and a new data indicator
indicating whether user data is initially transmitted or
retransmitted on the shared channel.
29. The control channel transmitting method of claim 21, wherein
the low-priority control information includes information about a
transport block set size of a transport channel mapped to the
shared channel, redundancy version information indicating a
redundancy bit combination used for retransmitted user data if the
user data is retransmitted, and an HARQ Process ID indicating a
number of a logical channel that transmits the user data.
30. The control channel transmitting method of claim 29, further
comprising the step of controlling the redundancy version
information not to be generated when the user data is initially
transmitted, and controlling the transport block set size
information not to be generated when the user data is
retransmitted.
31. A control channel receiving method in a communication system
including a shared channel and a control channel, the shared
channel being shared among a plurality of UEs (User Equipments) and
spread with a plurality of channelization codes, and the control
channel transmitting control information related to the shared
channel to enable the UEs to receive the shared channel, the method
comprising the steps of: receiving a control channel signal and
demultiplexing the control channel signal into high-priority
control information and low-priority control information according
to processing urgency degrees of the control information under a
predetermined control; decoding the high-priority control
information in a predetermined first decoding method; and decoding
the low-priority control information in a predetermined second
decoding method different from the first decoding method after
decoding the high-priority control information.
32. The control channel receiving method of claim 31, wherein the
high-priority control information includes information about a
channelization code to spread the shared channel with, and a
modulation scheme applied to the shared channel.
33. The control channel receiving method of claim 31, wherein the
low-priority control information includes information about a new
data indicator indicating whether user data is initially
transmitted or retransmitted on the shared channel, a transport
block set size of a transport channel mapped to the shared channel,
redundancy version information indicating a redundancy bit
combination used for retransmitted user data if the user data is
retransmitted, and an HARQ (Hybrid Automatic Repeat reQuest)
process ID (Identifier) indicating a number of a logical channel
that transmits the user data.
34. The control channel receiving method of claim 33, further
comprising the step of determining that the low-priority control
information includes the transport block set size information when
the user data is initial transmission data.
35. The control channel receiving method of claim 31, wherein the
high-priority control information includes information about a
channelization code to spread the shared channel with, and a new
data indicator indicating whether user data is initially
transmitted or retransmitted on the shared channel.
36. The control channel receiving method of claim 31, wherein the
low-priority control information includes information about a
modulation scheme applied to the shared channel, a transport block
set size of a transport channel mapped to the shared channel,
redundancy version information indicating a redundancy bit
combination used for retransmitted user data if the user data is
retransmitted, and an HARQ Process ID indicating a number of a
logical channel that transmits the user data.
37. The control channel receiving method of claim 36, further
comprising the step of determining that the low-priority control
information includes the transport block set size information when
the user data is initial transmission data.
38. The control channel receiving method of claim 31, wherein the
high-priority control information includes information about a
channelization code to spread the shared channel with, a modulation
scheme applied to the shared channel, and a new data indicator
indicating whether user data is initially transmitted or
retransmitted on the shared channel.
39. The control channel receiving method of claim 31, wherein the
low-priority control information includes information about a
transport block set size of a transport channel mapped to the
shared channel, redundancy version information indicating a
redundancy bit combination used for retransmitted user data if the
user data is retransmitted, and an HARQ Process ID indicating a
number of a logical channel that transmits the user data.
40. The control channel receiving method of claim 39, further
comprising the step of determining that the low-priority control
information includes the transport block set size information when
the user data is initial transmission data.
Description
[0001] This application claims priority to an application entitled
"Apparatus and Method for Transmitting/Receiving High Speed-Shared
Control Channel in a High Speed Downlink Packet Access
Communication System" filed in the Korean Industrial Property
Office on Dec. 28, 2001 and assigned Serial No. 2001-87296, the
contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to an HSDPA (High
Speed Downlink Packet Access) communication system, and in
particular, to an apparatus and method for transmitting/receiving
control information on a shared control channel.
[0004] 2. Description of the Related Art
[0005] In its earlier developmental stage, a mobile communication
system focused on voice service only. Now, user demands and
advanced mobile communication technology have developed a
high-speed, high-quality wireless packet communication system to
provide data service and multimedia service. Major efforts to
deploy a 2Mbps or higher-speed, high-quality wireless packet
service in a third-generation mobile communication system involve
ongoing standardization of HSDPA and 1xEV-DV (Evolution-Data and
Voice) in the 3GPP (3.sup.rd Generation Partnership Project) and
3GPP2 (3.sup.rd Generation Partnership Project 2). A
fourth-generation mobile communication system is being developed to
provide higher-speed, higher-quality multimedia service.
[0006] As its name implies, HSDPA provides high-speed packet data
service to terminals via an HS-DSCH (High Speed-Downlink Shared
Channel) and related control channels. To support HSDPA, AMC
(Adaptive Modulation and Encoding) and HARQ (Hybrid Automatic
Retransmission Request) have been proposed.
[0007] AMC is a technique for adapting a modulation and coding
format based on the received signal quality of a UE (User
Equipment) and the channel condition between a particular Node B
and the UE to increase the use efficiency of the entire cell.
Therefore, a plurality of modulation and coding schemes (MCSs) are
defined for AMC. MCS levels are defined from level 1 to level n. In
other words, the AMC is an adaptive selection of an MCS level
according to the channel condition between the UE and the serving
Node B.
[0008] In AMC, an MCS is changed according to a down-link channel
condition, which is represented usually as an SNR (Signal-to-Noise
Ratio) of a received signal in the UE. The UE feeds back the SNR to
the Node B on an up-link. The Node B then estimates the down-link
channel condition and selects an appropriate MCS based on the
estimation. Modulation schemes under consideration are QPSK
(Quadrature Phase Shift Keying), 8PSK, 16QAM (Quadrature Amplitude
Modulation), and 64QAM, and coding rates under consideration are
1/4, 1/2, and 3/4. The Node B selects a high-order modulation
scheme (e.g., 16QAM and 64QAM) and-a high coding rate (e.g., 3/4)
for a UE near to the center of the BS, that is, a UE in a good
channel condition, and a low-order modulation scheme and a low
coding rate (e.g., 1/2) for a remote UE, that is, a UE in a bad
channel condition. As compared to a conventional MCS determining
method relying on high-speed power control, interference is reduced
and thus system performance is improved.
[0009] HARQ is a link control scheme for retransmission of an
initial packet having errors in order to compensate for the errors.
HARQ techniques include CC (Chase Combining), FIR (Full Incremental
Redundancy), and PIR (Partial Incremental Redundancy).
[0010] In CC, the same packet as an initial transmission packet is
retransmitted. A receiver combines the retransmission packet with
the initial transmission packet stored in a reception buffer, thus
increasing the reliability of coded bits input to a decoder and
achieving an overall system performance gain. Since combining the
same two packets is similar in effect to repetition coding, an
average of an about 3-dB performance gain increase results.
[0011] In FIR, instead of retransmitting the same packet as an
initial transmission packet, a data packet having only redundancy
bits generated in a channel encoder is transmitted at a
retransmission. Since the decoder decodes using new redundancy bits
as well as the initial transmission packet, decoding performance is
increased.
[0012] As described above, to support HSDPA, new techniques such as
AMC and HARQ must be provided and new control information must be
exchanged between a UE and a Node B. The new control information is
delivered on an HS-SCCH (High Speed-Shared Control Channel), which
will be described with reference to FIG. 1.
[0013] FIG. 1 illustrates a structure of the HS-SCCH in a typical
HSDPA communication system. Referring to FIG. 1, the HS-SCCH
includes TFRI (Transport Format and Resource Related Information),
CRC (Cyclic Redundancy Check), and HARQ Information. The HS-SCCH
has a period of 2 ms because a data unit delivered on the HS-SCCH
is 3 slots (i.e., 2 ms). That is, the HS-SCCH has a TTI
(Transmission Time Interval) of 2 ms.
[0014] The HS-SCCH delivers the following control information:
[0015] 1) HS-DSCH (High Speed-Downlink Shared Channel)
channelization 5 code;
[0016] 2) Modulation scheme (MS);
[0017] 3) Transport block set size (TBSS);
[0018] 4) Transport channel identity (TrCH ID);
[0019] 5) UE-specific CRC;
[0020] 6) HARQ Process ID;
[0021] 7) New data indicator (NDI); and
[0022] 8) Redundancy version (RV).
[0023] MS, TBSS, TrCH ID, and HS-DSCH channelization code are
referred to as "TFRI information". The TFRI information is
delivered in the TFRI field. HARQ Process ID, RV, and NDI are
referred to as "HARQ information" which is delivered in the HARQ
field. The above control information will be described below in
more detail.
[0024] (1) HS-DSCH Channelization Code
[0025] In the HSDPA communication system, down-link transmission
resources are shared among a plurality of UEs. The down-link
transmission resources include OVSF (Orthogonal Variable Spreading
Factor) codes. It is under consideration to use 10, 12, or 15 OVSF
codes when SF=16 and 20 OVSF codes when SF=32 in the HSDPA
communication system. Assignment of OVSF codes in the HSDPA
communication system will be described with reference to FIG.
2.
[0026] FIG. 2 illustrates an OVSF code tree with an SF of 16 in the
typical HSDPA communication system. Referring to FIG. 2, each OVSF
code is expressed as C(i, j) according to its position in the code
tree. The variable i of C(i, j) represents the SF and the variable
j represents the position of the OVSF code counted from the left,
with the first position being numbered 0. For example, C(16, 0)
indicates the first OVSF code from the left when SF=16. For an SF
of 16, 10 OVSF codes C(16, 6) to C(16, 15) are assigned to the
HSDPA communication system in FIG. 2. The 10 OVSF codes can be
multiplexed for a plurality of UEs.
[0027] If there are HSDPA-supporting UEs A, B, and C, code
multiplexing can be performed with 4 OVSF codes assigned to A, 5
OVSF codes to B, and the other one to C. Considering the amount of
user data for each UE, a Node B determines the number of OVSF codes
to be assigned to the UE and their positions in the OVSF code
tree.
[0028] Use of 6 or 7 bits to represent information about
channelization codes assigned to the HS-DSCH is under consideration
in the present standardization work. For clarity of description, it
is assumed that the HS-DSCH channelization code information is
expressed in 7 bits.
[0029] (2) MS Information
[0030] As described before, a Node B selects an MCS adaptively
according to a down-link channel condition between the Node B and a
UE and tells the UE the MCS. Since the UE can determine the
selected coding rate using TBSS, TrCH ID, HS-DSCH channelization
ID, and MS, the Node B simply notifies the UE of the selected
modulation scheme. In the following description, it is assumed that
QPSK and 16QAM are available as modulation schemes and 1 bit is
assigned to indicate the selected modulation scheme.
[0031] (3) TrCH ID
[0032] A transport channel is characterized by how information is
transferred on a physical channel. In general, the transport
channel is defined in terms of coding rate, channel encoding,
transport block (TB) size, and the number of transmittable TBs
during one TTI. If there are two different transport channels, it
implies that they are different in terms of the above-described
items. Because a plurality of transport channels can be
time-division-multiplexed in an HS-PDSCH (High Speed-Physical
Downlink Shared Channel), a UE must know which transport channel is
active in the HS-PDSCH at a particular time. The transport channel
is identified by its TrCH ID.
[0033] (4) TBSS
[0034] TBSS indicates the number of TBs transmitted during one TTI,
so that a UE calculates the number of rate-matched bits in a
physical layer. Rate matching refers to how repetition or
puncturing is performed in the physical layer of a Node B. The rate
matching and the TBSS are in such a relationship that the former is
known from the latter. Therefore, a Node B does not transmit
information about the rate matching to the UE. As described before,
the TBSS is delivered in the TFRI field. Herein below, it is
assumed that 6 bits are assigned to the TrCH ID and TBSS
information.
[0035] (5) RV
[0036] If FIR is adopted as an HARQ technique, new redundancy bits
are generated at a retransmission of an initial data packet. The
Node B provides a redundancy bit combination indicator to the UE so
that the UE can demodulate the data packet correctly. The
redundancy bit combination indicator is an RV. It is assumed here
that 4 puncturing patterns are available for redundancy bits and
thus 2 bits are assigned to the RV.
[0037] (6) NDI and UE-Specific CRC
[0038] NDI indicates whether a data packet is initially transmitted
or retransmitted. It is assumed that the NDI information is
represented in one bit. UE-specific CRC makes a UE-specific ID more
reliable. It is assumed that the UE-specific CRC is 12 or 16 bits.
In the HS-SCCH slot format, the CRC field functions to check errors
in the TFRI field, or in both the TFRI and HARQ Information
fields.
[0039] (7) HARQ Process ID
[0040] Two techniques are used to increase HARQ efficiency. One is
to exchange a retransmission request and a response for the
retransmission request between the UE and the Node B, and the other
is to temporarily store defective data and combine it with
corresponding retransmitted data. In the HSDPA communication
system, an n-channel SAW HARQ has been introduced to overcome the
shortcomings of conventional SAW HARQ. In the conventional SAW
HARQ, the next packet data is not transmitted until an ACK
(Acknowledgement) signal is received for a current transmitted
packet data. This implies that even though the next packet data can
be transmitted, the ACK signal must be awaited. On the other hand,
the n-channel SAW HARQ allows successive transmission of the next
packet data without receiving an ACK signal for the current
transmitted packet data, thereby increasing channel use efficiency.
If n logical channels are established between a UE and a Node B and
identified by specific time or their channel numbers, the UE can
determine a channel on which a data packet has been transmitted at
an arbitrary time point. The UE also can rearrange packet data in
the right reception order or soft-combine corresponding packet
data. A logical channel that delivers a particular packet is
identified by an HARQ Process ID.
[0041] Table 1 below lists parameters delivered on the HS-SCCH and
their sizes.
1 TABLE 1 Parameter Size (bits) Channelization code set 7 MS 1 TrCH
ID + TBSS 6 CRC 16 HARQ Process ID 3 NDI 1 RV 2 Total 36
[0042] Now a description will be made of an HS-SCCH transmitter in
the typical HSDPA communication system with reference to FIG.
3.
[0043] Referring to FIG. 3, before transmitting user data to a UE
on an HS-DSCH, a Node B determines a channelization code 320 to be
assigned to the user data through a code assigner 302, and an MS
318 and a coding rate through an MCS controller 304. Since the UE
can determine the coding rate based on the MS 318, a TrCH ID &
TBSS 310, and the channelization code 320, the Node B does not
transmit information about the coding rate to the UE. An HARQ
controller 306 determines an NDI 316, an HARQ Process ID 314, and
an RV 312. A transport channel & block determiner 308
determines the TrCH ID & TBSS 310 for transmission of the user
data.
[0044] A multiplexer (MUX) 322 multiplexes the channelization code
320, the MS 318, the NDI 316, the HARQ Process ID 314, the RV 312,
and the TrCH ID & TBSS 310 to a bit stream in the HS-SCCH slot
format. A CRC encoder 324 adds a CRC to the bit stream, and a
serial-to-parallel converter (SPC) 326 converts the output of the
CRC encoder 324 to an I bit stream and a Q bit stream.
[0045] Multipliers 328 and 329 multiply the I and Q bit streams by
a predetermined spreading code C.sub.OVSF, respectively. The
multipliers 328 and 329 serve as spreaders. A multiplier 331
multiplies the output of the multiplier 329 by a signal component
j. An adder 330 generates a complex signal by summing the outputs
of the multipliers 328 and 331. A multiplier 332 multiplies the
complex signal by a predetermined scrambling code C.sub.SCRAMBLE.
Thus the multiplier 332 serves as a scrambler. A multiplier 334
multiplies the scrambled signal by a channel gain. A modulator 336
modulates the output of the multiplier 334 in the determined
modulation scheme. An RF (Radio Frequency) processor 338 converts
the modulated signal to an RF signal and transmits the RF signal in
the air through an antenna 340.
[0046] FIG. 4 is a block diagram of an HS-SCCH receiver in the
typical HSDPA communication system. Referring to FIG. 4, an RF
processor 404 converts an RF signal received from the air through
an antenna 402 to a baseband signal. A demodulator 406 demodulates
the baseband signal in a demodulation method in correspondence with
a modulation scheme used in the Node B. A multiplier 408 multiplies
the demodulated signal by the same scrambling code C.sub.SCRAMBLE
as used in the Node B. The multiplier 408 serves as a
descrambler.
[0047] A complex to I & Q stream unit 410 separates the
descrambled signal into an I bit stream and a Q bit stream.
Multipliers 412 and 414 multiply the I and Q bit streams by the
same spreading code C.sub.OVSF as used in the Node B, respectively.
The multipliers 412 and 414 serve as despreaders. A channel
compensator 416 compensates for distortion possibly produced during
signal transmission in the air.
[0048] A parallel-to-serial convert6er (PSC) 420 converts the
channel-compensated signals to a serial signal. A CRC decoder 422
checks the CRC of the serial signal. If the signal is normal, the
CRC decoder 422 feeds the signal to a demultiplexer (DEMUX) 424.
The DEMUX 424 demultiplexes the CRC-checked signal into
channelization code 426, MS 430, NDI 432, HARQ Process ID 434, RV
436, TrCH ID 438, and TBSS 440.
[0049] In the above-described HSDPA communication system, an
initial transmission packet and a retransmission packet are
transmitted with no distinction made between them. Control
information about them is also transmitted in corresponding fields
irrespective of initial transmission or retransmission, resulting
in waste of radio resources. A puncturing pattern is preset for the
initial transmission and thus there is no need for transmitting RV
information to a UE at the initial transmission. The TrCH ID 438
and the TBSS 440 are not changed at the initial transmission and a
retransmission. Therefore, it is unnecessary to transmit the TrCH
ID and TBSS information at both the initial transmission and
retransmission. It is because when an initial packet has errors,
the packet is retransmitted on the same transport channel and the
transport channel has the same TBSS. The indiscriminate data
transmission wastes radio resources assigned to the control
information. As a result, the overall system capacity is adversely
affected. While the control information is delivered sequentially
on the HS-SCCH at present, some control information may require
processing with priority for demodulation of an HS-PDSCH signal
related with the HS-SCCH signal. In this case, processing the
HS-PDSCH signal might be delayed.
SUMMARY OF THE INVENTION
[0050] It is, therefore, an object of the present invention to
provide an apparatus and method for transmitting minimum control
information about data packet transmission in an HSDPA
communication system.
[0051] It is another object of the present invention to provide an
apparatus and method for minimizing an amount of control
information to be transmitted on a shared control channel in an
HSDPA communication system.
[0052] It is a further object of the present invention to provide
an apparatus and method for transmitting minimum control
information about data packet transmission depending on whether the
packet transmission is an initial transmission or a retransmission
in an HSDPA communication system.
[0053] It is still another object of the present invention to
provide an apparatus and method for transmitting control
information on a shared control channel according to its priority
in an HSDPA communication system.
[0054] To achieve the above and other objects, according to one
aspect of the present invention, in a control channel transmitting
apparatus of a communication system including a shared channel,
shared among a plurality of UEs and spread with a plurality of
channelization codes, and a control channel for transmitting
control information related with the shared channel to enable the
UEs to receive the shared channel, a controller prioritizes the
control information according to the processing urgency degree of
the control information. A first control information generator
generates high-priority control information under the control of
the controller. A second control information generator generates
low-priority control information under the control of the
controller. A first encoder encodes the high-priority control
information in a predetermined first encoding method. A second
encoder encodes the low-priority control information in a
predetermined second encoding method different from the first
encoding method, and a MUX multiplexes the high-priority control
information and the low-priority control information to a control
channel signal such that the high-priority control information
precedes the low-priority control information.
[0055] According to another aspect of the present invention, in a
control channel receiving apparatus of a communication system
including a shared channel, shared among a plurality of UEs and
spread with a plurality of channelization codes, and a control
channel for transmitting control information related with the
shared channel to enable the UEs to receive the shared channel, a
DEMUX receives a control channel signal and demultiplexes the
control channel signal into high-priority control information and
low-priority control information according to the processing
urgency degrees of the control information under a predetermined
control. A first decoder decodes the high-priority control
information in a predetermined first decoding method. A second
decoder decodes the low-priority control information in a
predetermined second decoding method different from the first
decoding method, and a controller controls the high-priority
control information to be demodulated earlier than the low-priority
control information.
[0056] According to a further aspect of the present invention, in a
control channel transmitting method for a communication system
including a shared channel shared among a plurality of UEs and
spread with a plurality of channelization codes, and a control
channel for transmitting control information related with the
shared channel to enable the UEs to receive the shared channel, the
control information is prioritized according to a processing
urgency degree of the control information. High-priority control
information is generated and encoded in a predetermined first
encoding method. Low-priority control information is generated and
encoded in a predetermined second encoding method different from
the first encoding method, and the high-priority control
information and the low-priority control information are
multiplexed to a control channel signal such that the high-priority
control information precedes the low-priority control
information.
[0057] According to still another aspect of the present invention,
in a control channel receiving method for a communication system
including a shared channel, shared among a plurality of UEs and
spread with a plurality of channelization codes, and a control
channel for transmitting control information related with the
shared channel to enable the UEs to receive the shared channel. A
received control channel signal is demultiplexed into high-priority
control information and low-priority control information according
to the processing urgency degrees of the control information under
a predetermined control. The high-priority control information is
decoded in a predetermined first decoding method, and then the
low-priority control information is decoded in a predetermined
second decoding method different from the first decoding
method.
BRIEF DESCRIPTION OF THE DRAWINGS
[0058] The above and other objects, features and advantages of the
present invention will become more apparent from the following
detailed description when taken in conjunction with the
accompanying drawings in which:
[0059] FIG. 1 illustrates an HS-SCCH slot format in a conventional
HSDPA communication system;
[0060] FIG. 2 illustrates an exemplary OVSF code tree for the
conventional HSDPA communication system;
[0061] FIG. 3 is a block diagram of an HS-SCCH transmitter in the
conventional HSDPA communication system;
[0062] FIG. 4 is a block diagram of an HS-SCCH receiver in the
conventional HSDPA communication system;
[0063] FIG. 5 illustrates downlink channels in the conventional
HSDPA communication system;
[0064] FIG. 6 illustrates HI (HS-SCCH Indicator) information in the
conventional HSDPA communication system;
[0065] FIG. 7 is a block diagram of an HS-SCCH transmitter in an
HSDPA communication system according to an embodiment of the
present invention;
[0066] FIGS. 8A, 8B, and 8C illustrate embodiments of an HS-SCCH in
the HSDPA communication system according to the present
invention;
[0067] FIG. 9 is a block diagram of an HS-SCCH receiver in the
HSDPA communication system according to the embodiment of the
present invention;
[0068] FIG. 10 schematically illustrates a common field illustrated
in FIG. 8A;
[0069] FIG. 11 is a flowchart illustrating an HS-SCCH transmitting
operation in the HS-SCCH transmitter illustrated in FIG. 7; and
[0070] FIG. 12 is a flowchart illustrating an HS-SCCH receiving
operation in the HS-SCCH receiver illustrated in FIG. 9.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0071] Preferred embodiments of the present invention will be
described herein below with reference to the accompanying drawings.
In the following description, well-known functions or constructions
are not described in detail since they would obscure the invention
in unnecessary detail.
[0072] FIG. 5 illustrates downlink channels in an HSDPA
communication system, for example, Release 5. Referring to FIG. 5,
the downlink channels for Release 5 are the DL-DPCH
(Downlink-Dedicated Physical Channel), the HS-SCCH, and the
HS-DSCH.
[0073] In addition to fields for supporting voice service in an
existing non-HSDPA communication system, for example, Release 99,
the DL-DPCH has a novel field, HI (HS-DSCH Indicator) to indicate
whether a UE is to receive an HSDPA data packet on the HS-DSCH. If
the UE is to receive the HSDPA data packet, the HI may additionally
provide the channelization code of an HS-SCCH having control
information about the HSDPA packet data. Although part of HS-DSCH
control information can be transmitted on the DL-DPCH, the HI
usually indicates the HS-SCCH for the UE to receive. If the UE is
to receive an HSDPA packet, the HI is set to indicate the existence
of the HSDPA packet. On the other hand, in the absence of an HSDPA
packet directed to the UE, the HI is processed in DTX
(Discontinuous Transmission), that is, the HI is not
transmitted.
[0074] A Node B can establish up to 4 HS-SCCHs. To provide
information about the presence or absence of an HSDPA data packet
for a particular UE and information indicating an HS-SCCH that
delivers control information about the HSDPA data packet, 2 bits
are assigned to the HI. The control information of the HI will be
described later with reference to FIG. 6.
[0075] As illustrated in FIG. 5, one DL-DPCH time slot is 0.67 ms
and an HS-SCCH TTI is 3 slots (2 ms). An HS-DSCH TTI is also 2 ms
and the HS-DSCH is transmitted a predetermined time after the
HS-SCCH, enabling the UE to receive HS-DSCH control information on
the HS-SCCH before receiving the HS-DSCH.
[0076] FIG. 6 illustrates HI information in the HSDPA communication
system. Referring to FIG. 6, the HI indicates an HS-SCCH directed
to a particular UE in 2 bits. For example, if 4 HS-SCCHs are
available in the HSDPA communication system, they are numbered
correspondingly. Since 2 bits are assigned to the HI, the numbers
of the HS-SCCHs are in a one-to-one correspondence with HI values.
As illustrated in FIG. 6, if the HI is absent, it indicates that
there is no HSDPA data packet for the UE. If the HI is 00, it
indicates a first HS-SCCH, if the HI is 11, it indicates a second
HS-SCCH. If the HI is 01, it indicates a third HS-SCCH, and if the
HI is 10, it indicates a fourth HS-SCCH. Consequently, five pieces
of information can be represented with the 2-bit HI.
[0077] Upon receipt of the DL-DPCH, the UE demodulates information
bits in the HI field. If the information bits have been processed
in DTX, the UE determines that it is not to receive an HSDPA packet
and waits until the next TTI, continuously monitoring the DL-DPCH.
On the other hand, if the information bits indicate a particular
value, the UE receives an HS-SCCH signal indicated by the value.
The UE then detects control information required to demodulate an
HS-DSCH signal, that is, information about the channelization code,
MS, TBSS, TrCH ID, CRC, and HARQ Process ID of the HS-DSCH.
Finally, the UE demodulates the HS-DSCH signal using the control
information and thus detects the HSDPA data packet. As illustrated
in FIG. 5, the UE receives the DL-DPCH and the HS-SCCH before
receiving the HS-DSCH signal. Therefore, the Node B controls the
start of transmission of the DL-DPCH and the HS-SCCH to precede the
start of transmission of the HS-DSCH.
[0078] FIG. 7 is a block diagram of an HS-SCCH transmitter in an
HSDPA communication system according to an embodiment of the
present invention. Referring to FIG. 7, before transmitting user
data to a UE on an HS-DSCH, a Node B determines a channelization
code 712 to be assigned to the user data through a code assigner
702, and an MS 714 and a coding rate through an MCS controller 704.
Since the UE can determine the coding rate based on the MS 714, a
TrCH ID & TBSS 722, and the channelization code 712, the Node B
does not transmit information about the coding rate to the UE. An
HARQ controller 706 determines an NDI 716, an HARQ Process ID 718,
and an RV 720. A transport channel & block determiner 708
determines the TrCH ID & TBSS 722 for transmission of the user
data.
[0079] Simultaneously with the determination of the NDI 716, the
HARQ controller 706 determines whether to transmit the RV 720 or
the TrCH ID & TBSS 722. The NDI 716 indicates to the UE whether
an HSDPA data packet is initially transmitted or retransmitted. At
an initial transmission, that is, when the NDI 716 is N(1: true),
the HARQ controller 706 determines to transmit the TrCH ID &
TBSS 722 in a common field of the HS-SCCH. At a retransmission,
that is, when the NDI 716 is C(0: false), the HARQ controller 706
determines to transmit the RV 720 in the common field of the
HS-SCCH. Then, the HARQ controller 706 controls a switch 724 to
switch to the determined control information. The common field
containing the RV 720 or the TrCH ID & TBSS 722 is a novel
field proposed in the present invention and will be described later
with reference to FIGS. 8A, 8B, and 8C.
[0080] A MUX 726 multiplexes the channelization code information
712, the MS 714, the NDI 716, the HARQ Process ID 718, and the RV
720 or TrCH ID & TBSS 722 to a bit stream in the HS-SCCH slot
format. A CRC encoder 728 adds a CRC to the bit stream, and an SPC
730 converts the output of the CRC encoder 728 to an I bit stream
and a Q bit stream.
[0081] Multipliers 732 and 734 multiply the I and Q bit streams by
a predetermined spreading code C.sub.OVSF, respectively. The
multipliers 732 and 734 serve as spreaders. A multiplier 735
multiplies the output of the multiplier 734 by a signal component
j. An adder 736 generates a complex signal by summing the outputs
of the multipliers 732 and 735. A multiplier 738 multiplies the
complex signal by a predetermined scrambling code C.sub.SCRAMBLE.
Thus the multiplier 738 serves as a scrambler. A multiplier 740
multiplies the scrambled signal by a channel gain. A modulator 742
modulates the output of the multiplier 740 in the determined
modulation scheme. An RF processor 744 converts the modulated
signal to an RF signal and transmits the RF signal in the air
through an antenna 746.
[0082] FIGS. 8A, 8B, and 8C illustrate embodiments of an HS-SCCH in
the HSDPA communication system.
[0083] Referring to FIG. 8A, the HS-SCCH is divided into two parts,
i.e., part 1 and part 2. Part 1 delivers information about a
channelization code set and an MS, and part 2 delivers information
about an NDI, a TrCH ID &TBSS or RV, a CRC, and an HARQ Process
ID. The field including the TrCH ID &TBSS or RV is defined as a
common field. The channelization code set and the MS precede the
other control information on the HS-SCCH because the control
information of the HS-SCCH is used to extract an HSDPA data packet
from a demodulated HS-DSCH DSCH signal and thus the channelization
code and MS information is required first. Therefore, the control
information of the HS-SCCH is classified into two parts according
to its priority. According to the present invention, the control
information of the HS-SCCH is prioritized according to its degree
of processing urgency and high-priority control information is put
in the first place, so that the UE processes the HS-DSCH more
efficiently based on the control information of the HS-SCCH.
Arrangement of control information according to its priority
implies that different coding schemes are applied to control
information with different priority levels. This is well known and
its description is not provided here.
[0084] It is determined from the NDI preceding the common field
whether the common field contains the TrCH ID & TBSS or the RV.
If the NDI is N(1: true), indicating initial transmission, the
common field delivers the TrCH ID & TBSS, and if the NDI is
C(0: false), indicating retransmission, the common field delivers
the RV.
[0085] Referring to FIG. 8B, since the MS is low in its processing
urgency degree, the NDI and the MS are exchanged in position.
Therefore, the UE determines earlier whether control information in
part 2 relates with initial transmission or retransmission. In this
HS-SCCH structure, control information requiring earlier processing
can be transmitted in part 1.
[0086] Referring to FIG. 8C, the channelization code set, the MS,
and the NDI are placed in part 1. Thus a modulation delay is
prevented and it is determined earlier whether control information
in part 2 relates with initial transmission or retransmission. As
stated before, arrangement of the control information is system
implementation-dependent and the following description is made in
the context of the HS-SCCH structure illustrated in FIG. 8A by way
of example.
[0087] FIG. 9 is a block diagram of an HS-SCCH receiver in the
HSDPA communication system according to the embodiment of the
present invention. Referring to FIG. 9, an RF processor 904
converts an RF signal received from the air through an antenna 902
to a baseband signal. A demodulator 906 demodulates the baseband
signal in a demodulation method in correspondence with a modulation
scheme used in a transmitter of a Node B. A multiplier 908
multiplies the demodulated signal by the same scrambling code
C.sub.SCRAMBLE as used in the Node B. The multiplier 908 serves as
a descrambler.
[0088] A complex to I & Q stream unit 910 separates the
descrambled signal into an I bit stream and a Q bit stream.
Multipliers 912 and 914 multiply the I and Q bit streams by the
same spreading code C.sub.OVSF as used in the Node B, respectively.
The multipliers 912 and 914 serve as despreaders. A channel
compensator 916 compensates for distortion possibly produced during
signal transmission in the air.
[0089] A PSC 918 converts the channel-compensated signals to a
serial signal. A CRC decoder 920 checks the CRC of the serial
signal. If the signal is normal, the CRC decoder 920 feeds the
signal to a DEMUX 922. The DEMUX 922 demultiplexes the CRC-checked
signal into channelization code information 926, MS 928, NDI 938,
an HARQ Process ID 930, and an RV 934 or a TrCH ID & TBSS 936.
The NDI 938 output from the DEMUX 922 is fed to a selector 924. If
the NDI 938 is N(1: true), the selector 924 determines that a data
packet directed to a corresponding UE is an initial transmission
packet, and controls a switch 932 to switch to the TrCH ID &
TBSS 936. If the NDI 938 is C(0: false), the selector 924
determines that the data packet directed to the UE is a re
transmission packet, and controls the switch 932 to switch to the
RV 934.
[0090] FIG. 10 schematically illustrates the structure of the
common field illustrated in FIG. 8A. Referring to FIG. 10, if N
bits are used to deliver a TrCH ID & TBSS and M bits are used
to deliver an RV (generally N>M), (N-M) bits are unused at a
retransmission of an HSDPA data packet because the TrCH ID &
TBSS is transmitted at an initial transmission and the RV is
transmitted at the retransmission. The (N-M) bits can be utilized
as radio resources for various purposes: (1) to additionally
transmit control information of another field, that is, for double
transmission of the control information, (2) to increase
demodulation performance by bit insertion; (3) to be DTX-processed;
and (4) to be inserted as dummy bits.
[0091] As described above, different control information (i.e., RV
or TrCH ID & TBSS) is transmitted depending on whether a data
packet is initially transmitted or retransmitted, thereby saving
information bits assigned to the RV or TrCH ID & TBSS. To do
so, one common field is defined to deliver the RV or TrCH ID &
TBSS.
[0092] Table 2 below lists parameters delivered on the HS-SCCH
having the slot format illustrated in FIG. 8A and their sizes.
2 TABLE 2 Parameter Size (bits) Channelization Code Set 7 MS 1 TrCH
ID + TBSS 6 Or RV CRC 16 HARQ Process ID 3 NDI 1 Total 34
[0093] As compared to Table 1 illustrating parameters and their
sizes in the conventional HS-SCCH, the HS-SCCH illustrated in Table
2 requires 34 bits, 2 bits less than the conventional HS-SCCH.
Since only the 2-bit RV is transmitted at a retransmission of a
data packet, 4 bits are saved from the 6-bit common field. In the 4
bits, control information of another field requiring more reliable
transmission than any other control information can be transmitted,
or a value preset between a UE and a Node B can be inserted,
thereby achieving the additional benefit of an increased
demodulation probability. The 36 information bits of the
conventional HS-SCCH are reduced to 30 information bits in the
HS-SCCH of the present invention when a data packet is
retransmitted.
[0094] FIG. 11 is a flowchart illustrating an HS-SCCH transmitting
operation in the HS-SCCH transmitter illustrated in FIG. 7.
Referring to FIG. 11, a Node B generates control information about
user data for a particular UE before transmitting the user data to
the UE on an HS-DSCH in step 1104. The control information includes
information about a channelization code, an MS, an NDI, an HARQ
Process ID, an RV, and a TrCH ID & TBSS. In step 1106, the Node
B determines whether the data packet is initially transmitted or
retransmitted. In the case of an initial transmission, the Node B
selects the TrCH ID & TBSS information for a common field of an
HS-SCCH in step 1108. On the other hand, in the case of a
retransmission, the Node B selects the RV information for the
common field in step 1110.
[0095] The Node B then multiplexes the control information to a bit
stream in an HS-SCCH slot format in step 1112 and adds a CRC to the
multiplexed bit stream in step 1114. In step 1116, the Node B
converts the CRC-attached serial it stream to parallel I and Q bit
streams. The Node B spreads the I and Q bit streams with a
predetermined spreading code in step 1118 and generates a complex
signal by adding them in step 1120.
[0096] The Node B scrambles the complex signal with a predetermined
scrambling code in step 1122 and multiplies the scrambled signal by
a predetermined channel gain in step 1124. In step 1126, the Node B
modulates the gain-controlled signal in a predetermined modulation
scheme. Then the Node B converts the modulated signal to an RF
signal in step 1128 and transmits the RF signal in the air through
an antenna in step 1130.
[0097] FIG. 12 is a flowchart illustrating an HS-SCCH receiving
operation in the HS-SCCH receiver illustrated in FIG. 9. Referring
to FIG. 12, a UE receives data from the air through antenna in step
1204, converts the data to a baseband signal in step 1206, and
demodulates the baseband signal in a demodulation method
corresponding to a modulation scheme used in a transmitter of a
Node B in step 1208. In step 1210, the UE descrambles the
demodulated signal with the same scrambling code as used in the
Node B. The UE separates the descrambled signal into I and Q bit
streams in step 1212 and despreads the I and Q bit streams with the
same spreading code as used in the Node B in step 1214.
[0098] The UE channel-compensates the despread I and Q bit streams
in step 1216, converts the I and Q bit streams to a serial bit
stream in step 1218, and CRC-checks the serial bit stream in step
1220. If the bit stream is normal, the UE demultiplexes the
CRC-checked signal to control information in step 1222. The control
information includes information about a channelization code, an
MS, an NDI, an HARQ Process ID, an RV, and a TrCH ID &
TBSS.
[0099] In step 1224, the UE determines whether the NDI indicates an
initial transmission or a retransmission. If the NDI is N(1: true),
indicating the initial transmission, the UE outputs information in
a common field of the HS-SCCH as the RV information in step 1226.
If the NDI is C(0: false), indicating the retransmission, the UE
outputs information in the common field as the TrCH & TBSS
information in step 1228.
[0100] In accordance with the present invention, different control
information is transmitted on an HS-SCCH depending on whether an
HSDPA data packet is initially transmitted or retransmitted in an
HSDPA communication system. The resulting minimization of radio
resource consumption for the control information increases the
entire system capacity.
[0101] Information bits required for the control information are
minimized as compared to the number of information bits of the
conventional HS-SCCH. The resulting available bits can be utilized
for double transmission of high-priority control information,
thereby increasing system reliability.
[0102] The control information is prioritized according to its
degree of processing urgency and transmitted according to the
priority level. Therefore, the throughput of an HS-DSCH related
with the control information of the HS-SCCH increases.
Consequently, the HS-DSCH signal is processed rapidly, which leads
to rapid user data reception. Thus the whole HSDPA communication
system performance is improved.
[0103] While the invention has been shown and described with
reference to a certain preferred embodiment thereof, it will be
understood by those skilled in the art that various changes in form
and details may be made therein without departing from the spirit
and scope of the invention as defined by the appended claims.
* * * * *